Air conditioning apparatus



June 16, 1942. HANSON ,25

AIR CONDITIONING APPARATUS Filed June 4, 1938 37/)\ l L J S .59 I

INVENTOR ,Dars Hanson BY kauwfub ATTORNEY Patented June 16, 1942 AIR CONDITIONING APPARATUS Lars Hanson, Syracuse, N. Y., assignor to Carrier Corporation, Syracuse, N; Y., a corporation of Delaware Application June 4, 1938, Serial No. 211,761

2 Claims. 4 (Cl. 62-4) This invention relates to air conditioning, and more particularly to air conditioning apparatus including a refrigerating system of the compression type.

The general object of the invention is to provide an improved system for controlling and regulating the operation of an air conditioning apparatus including a refrigerant compressor driven by an internal combustion engineor the like.

It is an object of -theinvention to provide an apparatus of the type'referred to which may be used to particular advantage in the conditioning of vehicles such as buses and railway cars, and which may also be used to advantage in stationary installations, as in homes or the like.

sor, the supply of refrigerant the evaporator is interrupted.

Another feature of the invention resides in the provision of a valve-controlled bypass line connecting the discharge side of the compressor with the suction side thereof, means foropening the normally-closed valve during the interval during which the starting switch of the system is operated, and means for opening the valve at other times during the operation of the system when the evaporator or suction pressure falls below a predetermined point. The valvein the compressor bypass line is closed whenever nor-' mal compression action is to be provided.'

Another object of the invention is to provide a system of thetype referred to in which the supply of liquid refrigerant to the evaporator of the system is permitted onlywhen the compres sor ofthe system is operating at a desired relative y high speed.

Another object of the invention is to provide a system of the type referred to in which provision is made for unloading the compressor during starting-up periods, so that the compressor may attain a desired relatively high speed in a short time and without difilculty before the normal operating load is imposed thereon.

A further object of the invention is to provide a system of the type referred to in which provision is. made for cutting the compressor out-of fluid-compressing service whenever the load thereon fallsbelow a, predetermined point, while the compressor continues to be actuated by its associated driving means.

Other objectsof the invention are to-provide tem including receiver ll, evaporator 12 and Other objects, features and advantages of the invention will be more apparent from the following description to be read in connection with the accompanying drawing, in which: a

Fig. 1' diagrammatically represents an apparatus embodying the invention;

2 diagrammatically represents the wiring diagram and control system utilized in conjunction with the apparatus of Fig. l; and

Fig. 3 is a view-similar to Fig. 2 illustrating a modified wiring diagram.

Referring now to the drawing, the numeral l0 4 represents the condenser of a refrigerating syscompressor' l3, The compressor I3 is adapted to deliver compressed refrigerant to the condenser l0 through line It and the condenser discharges v into receiver ll through line [5. Liquid refriga system of the type referred to which is controlled automatically in such manner as to insure at all times the maintenance of desired atmospheric conditions in the area served by the appa ratus; which is reliable in operation; and which is relatively simple and inexpensive.

A feature of the invention resides in controlling the supply of liquid refrigerant to the evaporator of the system in accordance with the pressure inthe inlet passage of the engine or the like,

driving the compressor. -Whenever the pressure in the inlet passage is lowered sufliciently to in-' dicate that the engine, and hence the compressor, are operating at relatively high speed, iefrigerant may be supplied to the evaporator; and, whenever the pressurein the inletpassage increases beyond a predetermined point, indicating and 22 respectively in well-known manner.

exchange surfaces of the radiator 20. r I The condenser III is preferably cooled by the erant supply line G ls adapted to supply liquid refrigerant from he receiver I l to the evaporator l2, and l'lrepresents the gas suction line through which refrigerant is delivered from the evaporator to the inlet connection of compressor I3. Compressor I3 is driven in any suitable manner,

as through shaft l8, by an internal combustion engine or the like, designated 19. 'The engine 19 is provided witha customary cooling means such as radiator 20 to and from which the'engine is circulated through lines H A fan 23 is provided to circulate air over the circulation of air thereover and, as illustrated,

v arrangement shown in the drawing is intended as illustrative only and that any suitable condenser arrangement may be employed. Similara reduction in speed of the engine and compresmi a fan 24, driven-by shaft 18 through belt 25 serves to circulate air, through the condenser housing 26. It isto be understood, however, that the ly-, the'evaporator I2 is illustrated as being disheat preferably mounted beneath the floor level of the vehicle, while the evaporator and its associated fan 28 are preferably mounted within the body portion of the vehicle to be conditioned. Since various arrangements of this general type are well known in the art, no detailed description is required of the manner in which the apparatus may be mounted, or the manner in which desired air circulation and distribution may be effected.

It is to be understood that the engine I9 is provided for the principal purpose of operating the compressor, and where the invention is applied to an engine-operated vehicle, the engine I9 is distinct from and is provided in addition to the engine used for propelling such vehicle.

Considering more particuarly the control apparatus, the numeral 30 designates an expansion valve of any suitable type under the control of thermal bulb or the like 3 la, mounted in heat exchange relation with the suction line at the outlet end of evaporator l2. In a manner wellknown in the art, the-thermal bulb 3 la serves to regulate the degree of opening of expansion vafve 30 to provide the desired cooling effect within the evaporator I2. Valve 3 positioned in line l6, preferably between receiver [and expansion valve 30, is adapted to control the supply of refrigerant liquid from the receiver H to the expansion valve, the valve 3| preferably being of the on-and-off type. Suction line I1 is connected to compressor discharge line |.4 by bypass line 32 provided with a valve 33, the valve 33 preferably being designed either to permit relatively unrestricted flow through bypass line 32 or completely to interrupt the how of fluid through bypass line 32.

The suction manifold 34 of :engine I9 is pro- .vided with a pressure-responsive element 35 adapted to respond to changes in pressure in the suction manifold which occur in accordance with changes in the operating speed of the engine l9. Thus when the engine I9 is operating at relatively'low speed or-not at all, the pressure in manifold 34 will be relatively high, but as the speed of engine I9 is increased the pressure in suction manifold 34 will'be correspondingly decreased. v

Referring more particularly to Fig. 2, the nulenoid 44. When thestarting switch is in closed position the armature 41 is attracted to complete an electrical circuit including lead 46 and starting motor 49, which serves to'start the engine I! in a well-known manner. The motor 49 is of such type that it is disengaged from the engine |9 when the engine has attained a predetermined speed. The energization of motor 49 is interrupted when, after a short interval, the starting switch is opened by the operator. Lead 50, connecting to one of the terminals of switch 40 and to a signal device, such as lamp 5|, serves to give indicationof the fact that the starter switch is closed. The energization of signal switch 5| is interrupted whenever the switch 40 is in open position.

During the time that the starter switch 40 is closed, there, is established an electrical circuit including lead 42, switch 40, lead 52 and solenoid 53. Solenoid 53 is adapted to control valve 33 in bypass line 32, the valve being arranged to be opened whenever the solenoid 53 is energized.

Since solenoid valves of various types are wellknown in the art, and since the solenoid-controlled valve 33 does not per se, form part of the present invention, no further description of this element is deemed necessary. It will thus be observed that during the starting-up interval during which starting switch 40 is closed, the valve 33 is opened. Thus, as the engine l9 begins its operation, the gas which is discharged from the compressor is recirculated back to the intake of the compressor at substantially the suction pressure. Thus, there is no effective compressing action and the compressor is completely unloaded, the only force required to drive the compressor under such conditions being that necessary to overcome friction losses. Upon opening the starting switch 40 the energizationof solenoid 53 through lead 52' is interrupted. Thereafter theenergizationof solenoid 53 is controlled by a circuit including battery 4|, lead 42, switch 31, lead 54, lead 55, lead 56 and pressurecontrolled switch 51. The switch 51 is controlled by a pressure-responsive element 58 disposed in suction line l1, the arrangement being such that the switch 51 is closed whenever the pressuremeral 36 designates a switch panel or the like,-

provided with a pair of manually operable singlepole single-throw switches, designated 31 and 33 respectively. The numeral 39 designates a startf er switch provided with a double pole singlethrow switch designated 40.

"When it is desired to place the system in operation, the switches 31 and 38 are closed and the operator then presses the starting switch 40 to Closing the close the same for a short interval. switch 31 completes a circuit including battery 4|, lead 42 and motor 29, thus to place in operation the motor 29 driving fan 23 serving to circulate air. over the evaporator |2. Closing of. the starting switch 40 completes a circuit including battery 4|, lead 42, lead 43 and solenoid 44 of starter relay 45. Lead 46 leading from the battery 4| is discontinuous and the flow of electricity therethrough is dependent upon the attractionof armature 41 to the contacts by-the soestablished.

responsive element 58 indicates a suction pressure lower than a predetermined point. Ac-

cordingly, whenever there is a relatively high suction pressure in the suction line I1, indicating a need for active compressing action, the switch 51 is'in opened position, thus to prevent energ'ization of solenoid 53 and thus to maintain the valve 33 in closed position.

- In starting up the apparatus, the compressor is unloaded 'by energization of solenoid 53 through lead 52, as above explained; The operator maintains the starting switch 40 in closed position until the engine and compressor come up to speed. Thus during the starting-up period, the valve 33 is maintained in open position and the compressor is substantially completely unloaded. This continues until the engine and compressor have attained their intended relatively high speeds, after which the switch 40 is opened and normal operation of the/ system is The valve 3| controlling the supply of refrig -erant liquid from the receiver to the evap- Q orator I2 is controlledby solenoid 59 adapted to be energized by battery 4| through lead 42,

switch 37, lead '54, lead 55,-switch as and lead '60. In lead 60 is interposed a thermostatic switch 3| adapted to be closed whenever the enclosure to be conditioned requires cooling. Since thermostatic switches of thistype are wellknown in the art, no detailed description of this feature is deemed required. Also disposed in the lead 60.is a. pressure switch 62 which is controlled by pressure-responsive element 35 positioned in the suction manifold of the engine is.

' The function of valve 3| is to prevent the supply has been attained. Since the pressure in suction manifold 34 drops as the speed of the engine increases, the pressure-responsiveelement 35 is arranged to close pressure switch 62 only after the pressure in suction manifold 34 has fallen to a.

predetermined point, thus to indicate that the engine and compressor have attained the desired spee'd. Since' various types of such pressure.

switches are well-known in the art, no further description .of this feature is deemed required here, but it is to be observed that the-invention contemplates that the pressure-responsive element 35 may be disposed at any desired point in the inlet passage or passages'connecting with the engine l9, or in communication with such passages, and is not restricted to any-particular location of thiselement.

The lead 60 is preferably provided with a second pressure-controlled switch 63 under the control of pressure-responsive element 64 disposed in discharge line Id. The pressure switch 63 is normally closed but is adapted to be opened whenever the pressure in line ll rises above a predetermined point, so as to interrupt the supply of refrigerant to the evaporator.

To provide against continued operation of the engine l9 after the switch31 has been opened.

or whenever a similar break in the circuit occurs as by burning out of fuse 29a in'the circuit of fan 23, there is preferably provided a relay 5 which controls the grounding of the magneto 66 serving the engine l9. Solenoid 61 is adapted to be energized whenever switch 31 is closed, the circuit including battery ll, lead 4!, switch 31,

lead 54 and lead 68, When the solenoid I is energized, it attracts armature 53 thus to open leadflli connecting the magneto 55 to ground.

Whenever the switch .31 is open the energlzation of solenoid 61 is interrupted, the armature 9 completesthe continuity of lead II, groundin the magneto 66 and-thus interrupting operation of the engine l9. l The circuit ill the same as that illustrated in Fig. 2. However, there is provided an additional lead ll having a switch 12 and a resistance element '13. If it is desired to runthe motor "at reduced speed, as may be desired under winter omrating conditions when the fad is used'to circulate air over a suitable'heating device, the switch 12 is closed while the switch 31 is maintained open. The insertion of resistance I3 in the circuit of motor 23 will serve to reduce the speed thereof in a'man ner well understood. 3 4

Fig. 3 as illustrated contains an ignition switch I4 andan ignition coil 15 rather than the ma neto of Fig. 2,-the ignition coil being provided --with a suitable breaker I6 in a manner well understood. I

' trated in Fig. 3 is essentially trolling switch 6| is satisfied, indicating 'that there is no need for further conditioning of the conditioned enclosure, the switch BI is opened and the valve 3i is therefore closed. The compressor meanwhile continues to withdraw refri erant from the evaporator l2 until the pressure in the suction line H is sufliciently low to cause switch 51120 close whereby valve 33 in the compressor bypass line is opened to unload the compressor l2. During the remainder of the period during which there is no demand for cooling, the compressor l3, driven by the constantly operative engine I9, continues to operate without load. Upon a demand for cooling, the switch 6] is closed and the refrigerant supply valve 3| is opened. The supply of refrigerant to the evaporator and the evaporation thereof increases the suction pressure in line I! and this increase con-' tinues until the switch 51 is opened whereby the bypass valve 33 is closed. Normal operation is thereupon resumed asabove described, this operation being controlled entirely automatically.

Since many changes may be made in the invention without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall beinterpreted as illustrative only and not in a limiting sense, applicant limiting h self only as indicated in the appended claims. 4 11 claim:

1. In an apparatus of the character described including a condenser,.an evaporator and a compressor driven'by an internal combustion engine having a starting motor associated therewith, the

combination of a compressor suction line connecting said evaporator and said compressor, a

tion of said starting motor in accordance with compressor discharge line connecting said compressor and said condenser, a bypass line connecting said discharge line and said suction line, a normally closed valve in said bypass line, means for energizing said starting motor, means for'opening said valve whenever" said'starting motor is energized, whereby said engine may be started up with practically no load on the compressor, and means for controlling the opening and closing of said valve during operation of said compressor and subsequent to the de-energizachanges in the pressure in said suction line, said last-mentioned means serving to open said valve whenever said pressure falls below a predetermined point, said starting motor being adapted to bev de-energized after said engine has been placed in normal operation. i v

' 2. In an apparatus of the character described including a condenser, an evaporator and a compressor driven by an internal combustion engine having a starting motor associated therewith, the combination of means for bypassing to the inlet of said compressor fluid discharged from the discharge side of said compressor, means for rendering operative said last-mentioned means whenever said starting motor is energized, and

- means for rendering operative said bypass means -whenever the pressure of refrigerant delivered from said evaporator falls below a predetermined of is prevented except when said starting motor.

is energized or the pressure of refrigerant delivered from said evaporator falls below a predetermined point.

. LARS HANSON. 

